This invention relates to a flywheel or a reaction wheel particularly for use in satellites or other space vehicles. The flywheel includes a bearing assembly of the known type which has two axially spaced rolling-element bearings (hereafter "ball bearings") which are surrounded by a hub sleeve and which are arranged on a stationary (non-rotating) core. The inner rings of the two ball bearings as well as the outer rings thereof are axially biased towards one another and are in engagement with an interposed inner spacer sleeve (for the inner rings) and an interposed outer spacer sleeve (for the outer rings).
A flywheel or a reaction wheel for the above-outlined purpose is disclosed in German Laid-Open Application (Offenlegungsschrift) No. 22 25 925. The structure disclosed therein has, at its outer radius, an annular flywheel mass which is connected with the hub by means of connecting elements, such as spokes. These connecting elements are provided with additional means, such as a stressed (biased) annulus for dampening oscillations or vibrations which are generated, for example, during the launching of the rocket carrying the space vehicle incorporating the flywheel. These dampening means may also find application in the structure designed according to the invention. They are, however, not an essential component thereof.
In a reaction wheel or flywheel of the above-outlined type in which biasing of the bearing unit or, more particularly, the biasing of the ball bearings towards one another is effected by means of a fixed clamping of the ball bearing rings with the intermediary of spacer sleeves, large mechanical stresses exerted on the bearing unit, for example, during the launching of the carrier rocket, can lead to permanent deformations within the bearing unit.